RIP, Ralph Kiner: Curing Man with a Shot in the Buttocks since 1922

It is noteworthy that the sulfonamids, penicillin, came in about simultaneously with Ted Williams, Ralph Kiner and the rubber ball. We want home runs, antibiotics to “cure” man with a single shot in the buttocks.
– William Carlos Williams, “Autobiography”
I dont understand what s single shot in the buttocks will cure.
But it will get you a purple heart and a trip to see the president of the US of A.